Shot: …doctrine cannot be preserved without allowing it to develop, nor can it be tied to an interpretation that is rigid and immutable without demeaning the working of the Holy Spirit. Pope Francis, 11 October 2017 Chaser: nothing of the things appointed ought to be diminished; nothing changed; nothing added; but they must be preserved both as regards expression and meaning. Pope Saint Agatho, as quoted by Pope Gregory XVI in Mirari Vos